•More common in primary infection
–Seen 3-6 months following exposure.
–29-38% of adults, uncommon in children.
–Typically unilateral on side of 10 infection.
–Only sign of disease in 5%.
–May precede appearance of parenchymal lung disease.
•Less common in postprimary disease
•Pleural fluid culture (+) in 20-40%
•Closed pleural Bx (+) in 65-75%
•True empyema--smears and cx usually positive